Computer systems include numerous electrical components that draw electrical current to perform their intended functions. For example, a computer's microprocessor or central processing unit (“CPU”) requires electrical current to perform many functions such as controlling the overall operations of the computer system and performing various numerical calculations. Generally, any electrical device through which electrical current flows produces heat. The amount of heat any one device generates generally is a function of the amount of current flowing through the device.
Typically, an electrical device is designed to operate correctly within a predetermined temperature range. If the temperature exceeds the predetermined range (i.e., the device becomes too hot or too cold), the device may not function correctly, thereby potentially degrading the overall performance of the computer system. Thus, many computer systems include cooling systems to regulate the temperature of their electrical components. One type of cooling system is a forced air system that relies on one or more air movers to blow air over the electronic components in order to cool the components.
The cubic feet per minute (“CFM”) of air that can be moved across an electric device is an important factor in how much heat can be removed from the device. Thus, the capacity of an air mover is a critical factor in selecting an air mover for use in a cooling application. The CFM that an air mover can produce is governed by total area of the blades generating the airflow and the free area provided for airflow through the air mover. The free area is defined as the cross-sectional area available to the airflow as it travels through the air mover. The total area of the blades is the cross-sectional area of the airflow as it passes through the rotating blades. In order to minimize choking of the airflow, the total area of the blades is often limited to the minimum free area of the airflow.
In many computer applications, the diameter of an air mover, and thus the CFM that it can produce, is limited by the height available within the computer chassis. Therefore, as can be appreciated there remains a need in the art for air movers that provide high volumes of airflow with limited heights.